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net_sched: sch_fq_codel: implement lockless fq_codel_dump()

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Instead of relying on RTNL, fq_codel_dump() can use READ_ONCE()
annotations, paired with WRITE_ONCE() ones in fq_codel_change().

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2024-04-18 07:32:43 +00:00 committed by David S. Miller
parent 01daf66b79
commit 396a003850
1 changed files with 35 additions and 22 deletions
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57
net/sched/sch_fq_codel.c
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@ -396,40 +396,49 @@ static int fq_codel_change(struct Qdisc *sch, struct nlattr *opt,
if (tb[TCA_FQ_CODEL_TARGET]) {
u64 target = nla_get_u32(tb[TCA_FQ_CODEL_TARGET]);
q->cparams.target = (target * NSEC_PER_USEC) >> CODEL_SHIFT;
WRITE_ONCE(q->cparams.target,
(target * NSEC_PER_USEC) >> CODEL_SHIFT);
}
if (tb[TCA_FQ_CODEL_CE_THRESHOLD]) {
u64 val = nla_get_u32(tb[TCA_FQ_CODEL_CE_THRESHOLD]);
q->cparams.ce_threshold = (val * NSEC_PER_USEC) >> CODEL_SHIFT;
WRITE_ONCE(q->cparams.ce_threshold,
(val * NSEC_PER_USEC) >> CODEL_SHIFT);
}
if (tb[TCA_FQ_CODEL_CE_THRESHOLD_SELECTOR])
q->cparams.ce_threshold_selector = nla_get_u8(tb[TCA_FQ_CODEL_CE_THRESHOLD_SELECTOR]);
WRITE_ONCE(q->cparams.ce_threshold_selector,
nla_get_u8(tb[TCA_FQ_CODEL_CE_THRESHOLD_SELECTOR]));
if (tb[TCA_FQ_CODEL_CE_THRESHOLD_MASK])
q->cparams.ce_threshold_mask = nla_get_u8(tb[TCA_FQ_CODEL_CE_THRESHOLD_MASK]);
WRITE_ONCE(q->cparams.ce_threshold_mask,
nla_get_u8(tb[TCA_FQ_CODEL_CE_THRESHOLD_MASK]));
if (tb[TCA_FQ_CODEL_INTERVAL]) {
u64 interval = nla_get_u32(tb[TCA_FQ_CODEL_INTERVAL]);
q->cparams.interval = (interval * NSEC_PER_USEC) >> CODEL_SHIFT;
WRITE_ONCE(q->cparams.interval,
(interval * NSEC_PER_USEC) >> CODEL_SHIFT);
}
if (tb[TCA_FQ_CODEL_LIMIT])
sch->limit = nla_get_u32(tb[TCA_FQ_CODEL_LIMIT]);
WRITE_ONCE(sch->limit,
nla_get_u32(tb[TCA_FQ_CODEL_LIMIT]));
if (tb[TCA_FQ_CODEL_ECN])
q->cparams.ecn = !!nla_get_u32(tb[TCA_FQ_CODEL_ECN]);
WRITE_ONCE(q->cparams.ecn,
!!nla_get_u32(tb[TCA_FQ_CODEL_ECN]));
if (quantum)
q->quantum = quantum;
WRITE_ONCE(q->quantum, quantum);
if (tb[TCA_FQ_CODEL_DROP_BATCH_SIZE])
q->drop_batch_size = max(1U, nla_get_u32(tb[TCA_FQ_CODEL_DROP_BATCH_SIZE]));
WRITE_ONCE(q->drop_batch_size,
max(1U, nla_get_u32(tb[TCA_FQ_CODEL_DROP_BATCH_SIZE])));
if (tb[TCA_FQ_CODEL_MEMORY_LIMIT])
q->memory_limit = min(1U << 31, nla_get_u32(tb[TCA_FQ_CODEL_MEMORY_LIMIT]));
WRITE_ONCE(q->memory_limit,
min(1U << 31, nla_get_u32(tb[TCA_FQ_CODEL_MEMORY_LIMIT])));
while (sch->q.qlen > sch->limit ||
q->memory_usage > q->memory_limit) {
@ -522,6 +531,7 @@ init_failure:
static int fq_codel_dump(struct Qdisc *sch, struct sk_buff *skb)
{
struct fq_codel_sched_data *q = qdisc_priv(sch);
codel_time_t ce_threshold;
struct nlattr *opts;
opts = nla_nest_start_noflag(skb, TCA_OPTIONS);
@ -529,30 +539,33 @@ static int fq_codel_dump(struct Qdisc *sch, struct sk_buff *skb)
goto nla_put_failure;
if (nla_put_u32(skb, TCA_FQ_CODEL_TARGET,
codel_time_to_us(q->cparams.target)) ||
codel_time_to_us(READ_ONCE(q->cparams.target))) ||
nla_put_u32(skb, TCA_FQ_CODEL_LIMIT,
sch->limit) ||
READ_ONCE(sch->limit)) ||
nla_put_u32(skb, TCA_FQ_CODEL_INTERVAL,
codel_time_to_us(q->cparams.interval)) ||
codel_time_to_us(READ_ONCE(q->cparams.interval))) ||
nla_put_u32(skb, TCA_FQ_CODEL_ECN,
q->cparams.ecn) ||
READ_ONCE(q->cparams.ecn)) ||
nla_put_u32(skb, TCA_FQ_CODEL_QUANTUM,
q->quantum) ||
READ_ONCE(q->quantum)) ||
nla_put_u32(skb, TCA_FQ_CODEL_DROP_BATCH_SIZE,
q->drop_batch_size) ||
READ_ONCE(q->drop_batch_size)) ||
nla_put_u32(skb, TCA_FQ_CODEL_MEMORY_LIMIT,
q->memory_limit) ||
READ_ONCE(q->memory_limit)) ||
nla_put_u32(skb, TCA_FQ_CODEL_FLOWS,
q->flows_cnt))
READ_ONCE(q->flows_cnt)))
goto nla_put_failure;
if (q->cparams.ce_threshold != CODEL_DISABLED_THRESHOLD) {
ce_threshold = READ_ONCE(q->cparams.ce_threshold);
if (ce_threshold != CODEL_DISABLED_THRESHOLD) {
if (nla_put_u32(skb, TCA_FQ_CODEL_CE_THRESHOLD,
codel_time_to_us(q->cparams.ce_threshold)))
codel_time_to_us(ce_threshold)))
goto nla_put_failure;
if (nla_put_u8(skb, TCA_FQ_CODEL_CE_THRESHOLD_SELECTOR, q->cparams.ce_threshold_selector))
if (nla_put_u8(skb, TCA_FQ_CODEL_CE_THRESHOLD_SELECTOR,
READ_ONCE(q->cparams.ce_threshold_selector)))
goto nla_put_failure;
if (nla_put_u8(skb, TCA_FQ_CODEL_CE_THRESHOLD_MASK, q->cparams.ce_threshold_mask))
if (nla_put_u8(skb, TCA_FQ_CODEL_CE_THRESHOLD_MASK,
READ_ONCE(q->cparams.ce_threshold_mask)))
goto nla_put_failure;
}